<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>task1.5</title>
</head>
<style type="text/css">
	#box{
		width:400px;
		height:200px;
		background:#ccc;
		position:absolute;
		margin:auto;
		top: 0; 
		left: 0; 
		bottom: 0; 
		right: 0;  
	}
	#box .circle1{
		width:50px;
		height:50px;
		border-bottom-right-radius:50px;
		background:#fc0;
	}
	#box .circle2{
		width:50px;
		height:50px;
		border-top-left-radius:50px;
		background:#fc0;
		position:absolute;
		bottom:0px;
		right:0px;
	}
</style>
<body>
	<div id="box">
		<div class="circle1"></div>
		<div class="circle2"></div>
	</div>
</body>
</html>